Adjusting SPF wheel bearings.

[Alan Watkins]

Originally Posted by RWoerz

Question, the bolts holding the caliper and the ones on the CV joint are all 10mm, I torqued them to 45ft/lbs. What should they be torqued to?

My torque table for metric fasteners says for coarse thread (1.25 mm):

standard (71K psi): 31
grade 8 (114k psi): 40
grade 10 (142K psi): 45
grade 12 (171K psi): 49

So assuming the hub (or whatever) material is similar in strength 45 seems OK.

BTW I just found better torque tables that covers both dry and lubed:

http://www.cncexpo.com/TorqueSpecs.aspx

[Alan Watkins]

Originally Posted by RWoerz

If you look at page 8 and the drawing of the AK

I'm kinda confused. Our cars use the AV seal, right? That's the one on the left of the three drawings on page 8.

But you're the one with the thing all opened up. Isn't it true that the seal OD is slightly smaller than the outer race OD, and the seal ID is about the same as the shaft OD? If not I've totally lost my situational awareness....

About the bearing removal issue, I'm not sure I know exactly which removal you're talking about. You mean removing the outer race of the outer bearing from the upright? If so I see the problem. The only thing I can think of is you are supposed to do it be de-shrinking the upright, i.e. heat it while possibly cooling the race and it falls out. (yeah right).

But your seals on both sides came right out, so you must be talking about a press fit of the inner races (cones) onto the axle...?? In that case the inner cone comes off when you press the axle out, and the outer cone .... stays stuck to the axle with no obvious way to remove it (other than heat and dry ice). Is that the problem?

Short of a shop manual, even something like "here are assembly/disassembly notes that even a sophisticated mechanic might need" would be a huge help. And maybe some torque figures for non-obvious situations. After all, somebody has to maintain these things and much as I'd like to I can't afford to ship my car to Mt. Ulla every time it needs its bearings adjusted. Oh I know, I'll take it to my local Shell Station. They'll know what to do.

[Richard]

Honestly I was thinking this whole AV/AK thing was something someone had made up, well I was wrong. As you will see from the pictures SPF does indeed us an AV style of seals. This however does not mean that it’s a good thing and after looking at my parts I don’t think the people putting them together understand the delicate relationship between these parts. I was suppose to leave for a long trip now I’m not so sure. The seal and bearing shown is the inner set (closer to the transaxle).

[Alan Watkins]

Originally Posted by RWoerz

The seal and bearing shown is the inner set (closer to the transaxle).

In the first two photos I see nice neat groove like I would expect the seal to make. Looks nice, I think.

In the second two photos I'm not completely sure what I'm looking at but I assume it's the rolling surface of the outer race and toward it's outer edge is a rough area. If that's right, is that rough are a part that rollers run on? Either way, where'd it come from?

5 & 6 show battered seals. You're saying that hitech did that installing them? Yikes. At least it doesn't look like they distorted the "cutting edge" much.

7-9 I assume is just to identify the bearings.

The seals are about $25 each from Motion Industries. An NTT 18690 cone from them is about $30. And the 18620 cup that goes with it is about $15. So if the prices are the same for the other side of each hub, we're at ~$70 x 4 to replace everything. But I can't tell if anything's wrong with the bearings. If not, I think the thing to do is replace all the seals just because they're dented and put it back together.

Trouible is I have a conflict of interest cuz I don't want you to miss you're trip to CA.

[Richard]

Photos 3 and 4 are of the inner race. At first I didn't see the groove. It was only after I cropped and zoomed in did I find it. I've used a local bearing supplier for may years and according to them the seals are currently unavailable and SKF does not have a production date. If anyone knows where I can get a set please let me know.

Sorry to say my Calif. trip is on hold but I still hope to leave next week.

[Alan Watkins]

Originally Posted by RWoerz

Photos 3 and 4 are of the inner race. At first I didn't see the groove. It was only after I cropped and zoomed in did I find it. I've used a local bearing supplier for may years and according to them the seals are currently unavailable and SKF does not have a production date. If anyone knows where I can get a set please let me know.

Sorry to say my Calif. trip is on hold but I still hope to leave next week.

Richard --

I just called my local branch of Motion Industries who have ordered me a pair of each coming from the east coast by 2nd day air. Apparently (but I don't know this for sure yet) they come as a pair, inner and outer, for each bearing size. So my rep. said the best way to order them is by item number, as follows:

18690/18620 - item 02320532 $21.98 ea. (18 in stock)
18790/18720 - item 02107182 $20.31 ea. (10 in stock)

He said the best thing for you to do is contact your local branch (Boise or Pocatello) and order from them. If that fails in some way you're welcome to the ones I will presumably have next Tuesday or so.

Motion Industries - Locations

[Richard]

So you have to buy the bearings to get the seals?

[Alan Watkins]

Originally Posted by RWoerz

So you have to buy the bearings to get the seals?

No, sorry, I should have said "seals for bearing part numbers 18690 &18620" rather than just "18690/18620 "

The seals and the bearings use essentially the same part numbers. The seal part number is the bearing part number followed by "AV." So taking the outer (larger) bearing as an example:

• the bearing cone (inner race plus rollers) part number is 18790,
• the seal for the cone part number is 18790AV,
• the cup (outer race) part number is 18720,
• the seal for the cup is 18720AV.

Furthermore we (my Motion Industries rep and I) believe the cone seal and cup seal ship as a pair as item number 02107182 for $24.33 (which is good news because that makes them half as expensive as I thought they were).

[Steve C]

Alan,

So bottom line is that the seals are correct for the bearings and do in fact offer protection?

The thread never really came to a conclusion but, from my understanding SPF did research the seals issue and feels they are adequate protection.

Would be good tom have a conclusion for all.

Tx, Steve p2125

[Alan Watkins]

Originally Posted by steve c

So bottom line is that the seals are correct for the bearings and do in fact offer protection?

The thread never really came to a conclusion but, from my understanding SPF did research the seals issue and feels they are adequate protection.

I'm an electrical not mechanical engineer but the principle of the seals seems sound (and very clever) to me (wear a groove in the outer race and allow grease to migrate into it to serve as a seal). No doubt it is not as long-lasting nor as strong a barrier to water/dirt ingress as a typical spring loaded lip bearing, but they take up little space, required no pressing or prying, and the seal (grease) is renewable in a way that is consistent with race/exotic car maintenance.

As for SPF's research and feelings... How would I know? I'm only a customer...

But at a minimum this is the way GT40s were built in the first place so they are definitely "correct."

OTOH, the seals are relaively fragile and their sealing action could be compromised or destroyed by any ham-fistedness on the part of a mechanic (or factory assembler). Richard's show signs of having been ham-fisted (oh, that is an unfortunate verb) at the factory.

Anyway, for what it's worth, I think they're quite elegant as a mechanical problem solution but I think anyone who is maintaining a GT40 needs to be aware of them and their foibles. My intuition is that the hubs should be disassembled at worst annually to clean and restore the grease seal, otherwise the seal will disappear on its own and allow dirt in as well as the natural temperature-driven breathing action of the hub will allow water to collect and eventually wear and corrode the bearings.

And as usual, if it weren't for this forum (and for Carroll Smith, RIP) I would never have known, and had I been so unlucky as to have taken my hubs apart for some reason and NOT known what those things were I probably would have treated them as "dust shields" and possibly would have ruined them.

And that pretty much sucks, but I'm not going to beat the documentation dead horse any further, because I suspect it's a waste of energy. You know, don't try to teach a pig to sing and all that....

That's just my opinion. I'd like to hear from the mechanical illuminati in the crowd.

[Jac Mac]

Since when did these seals become 2-piece, I only see one piece units, there were some two piece seals on the website, but they are totally different in layout to what you have there. Your essentially stating that the one seal has two part #'s, 18790AV /18720AV

[Alan Watkins]

Originally Posted by jac mac

Since when did these seals become 2-piece, I only see one piece units, there were some two piece seals on the website, but they are totally different in layout to what you have there. Your essentially stating that the one seal has two part #'s, 18790AV /18720AV

You're right. I was thinking there is a seal on both sides of each bearing. Now that I re-read the part number scheme in the Nilos document and look again at Richard's photos I realize that there is one seal number for each pair of cup and cone, and that the seal goes only on the outside (flat face of cup side), so the format for the seal part number is "<cone #> / <cup #> AV", eg "18790/18720 AV" which makes more sense and means the rear end of a GT40 uses two each.

So what I should have said in post #88 is:

"The seal part numbers incorporate the bearing part numbers. The seal part number is the bearing cup part number followed by the bearing cone part number followed by "AV." So taking the outer (larger) bearing as an example:

• the bearing cone (inner race plus rollers) part number is 18790,
• the cup (outer race) part number is 18720,
• the seal for that cup/cone pair is 18790/18720 AV."

Also, BTW, disregard the $24.33 price. The correct prices are those in post #86.